Trichuris muris: effect of concurrent infections with rodent piroplasms on immune expulsion from mice.

Mice concurrently infected with the rodent piroplasms Babesia hylomysci or B. microti during a primary infection with the nematode Trichuris muris showed marked immunodepression, and the normal immune expulsion of the nematode was delayed. Immunodepression was most severe when the Babesia infections reached peak parasitaemia during the preexpulsion phase of the worm infection. Decline in parasitaemia to subpatent levels was associated with a reappearance of the immune response and expulsion of the worm. Babesia infections had little effect upon the expulsion of challenge infections of T. muris from mice previously immunized against the worm. Acute Babesia infections were found to exert a profound immunodepressive effect upon the agglutinating antibody response of mice to sheep red blood cells.     

Theileria annulata and Babesia ovis: ultracytochemical lactic dehydrogenase activity of sporozoites in salivary glands of female ticks, Hyalomma anatolicum excavatum and Rhipicephalus bursa

The occurrence of a marker enzyme of glycolysis, lactic dehydrogenase (LDH) (EC 1.1.1.27.), was studied ultracytochemically in sporozoites of Babesia ovis in the tick Rhipicephalus bursa and in sporozoites of Theileria annulata in the tick Hyalomma anatolicum excavatum. Female ticks infected transstadially were fed on rabbits and dissected 3–5 days post infestationem. The salivary glands were removed and incubated in the cytochemical medium unfixed or after fixation in buffered paraformaldehyde solution. A modified ferricyanide medium adjusted to pH 6.5 was used for incubation. Controls were performed by preincubating specimens in 10^?3 M iodine or by omitting NAD⁺ or lactate in the incubation medium. Following incubation, the specimens were fixed in buffered solutions of paraformaldehyde or glutaraldehyde, postfixed in osmium tetroxide, and embedded in Durcupan ACM. Mature “schizonts” consisting of an abundant number of sporozoites were examined in both piroplasmean species. In sporozoites of B. ovis the final enzymic product was deposited within the nucleus. No cytoplasmic reaction was observed. However, the membrane delimiting the schizont from the adjacent glandular cells was distinctly reactive. In T. annulata reactivity was usually confined to the cytoplasm. Sometimes, a reaction within mitochondria could be observed. The reaction product had formed aggregations which often appeared to be attached to micronemes. There was no nuclear reactivity in this species.The results suggest the existence of a glycolytic metabolic pathway with different subcellular localizations in sporozoites of the two piroplasmean species.     

There are at least three genetically distinct small piroplasms from dogs

The 18S nuclear subunit ribosomal RNA (18S rRNA) gene of small piroplasms isolated from dogs from Okinawa (Japan), Oklahoma, North Carolina, Indiana, Missouri, and Alabama, was isolated and sequenced. Phylogenetic analysis of these sequences and comparisons with sequences from other Babesia, Cytauxzoon, and Theileria species revealed that all canine small babesial isolates, with the exception of isolates from California and Spain, were placed in a group containing the Babesia spp. sensu stricto. Within the Babesia spp. sensu stricto, there was support for separating the small canine piroplasms from the large canine piroplasm, Babesia canis. The isolate from California was in a distinct phylogenetic clade, closely related to babesial isolates from wildlife and humans from the Western US. The canine isolate from Spain was closely related to Babesia microti. These results suggest that there are multiple small piroplasm species in dogs. The isolates from the Midwestern and Eastern US and the one from Japan probably represent a single species with wide geographic distribution.